FracBot Technology for Mapping Hydraulic Fractures

Summary Miniaturized transponder systems are under development for monitoring unconventional reservoirs, mapping hydraulic fractures, and determining other wellbore parameters. These gadgets are an extension of radio-frequency identification (RFID) and are known as fracture robot (FracBot) nodes to recognize wireless underground sensor networks (WUSNs) for characterization and mapping of hydraulic breakages in unconventional reservoirs. 3D constellation maps of proppant-bed placement are generated by autonomous localization algorithms as FracBots are injected during hydraulic-fracturing operations. To investigate this model, a FracBot platform was established to explore this concept, and three basic functions have been explained. First, we have developed an innovative cross-layer communication model for magnetic-induction (MI) networks in altering underground environments, coupled with selections of coding, modulation, and power control and a geographic forwarding structure. Second, we have developed an innovative MI-based localization framework to capture the locations of the randomly deployed FracBot nodes by exploiting the exceptional properties of the MI field. Third, we have proposed an energy model for a linear FracBot network scheme that provides reasonable data rates while preserving collected energy limitations. Finally, to examine the functionalities of FracBot nodes in air, sand, and stone media, a physical MI-based WUSN test bed was implemented. Experiments indicated that the constructed FracBots can form a communication link and transfer data over amplitude-shift keying (ASK) modulation with 1.6 kbit/sec as a data rate and a minimum receiver sensitivity of −70 dBm. The performance of near-field-communication (NFC) antennas was affected by sand and stone media, which ultimately affect MI signal propagation and decrease the energy transfer. In sand or stone media, augmented mismatch between transmitter and receiver antennas was detected, leading to the decision that an advanced matching circuit design or an adaptive-frequency feature should be integrated into the FracBot design. This permits an optimal energy transmission and consistent communication link through sand and stone media.